题解 | #记录点赞用户#

import java.util.*;

public class Main {

public static void main(String[] args) {
    LikeRecorder recorder = new LikeRecorderImpl();

    Scanner scanner = new Scanner(System.in);
    while (scanner.hasNext()) {
        String name = scanner.next();
        recorder.like(name);
    }

    System.out.println(Arrays.toString(recorder.getLikeUsers()));
}

}

/**

• 点赞记录器 */ interface LikeRecorder {

  /**

  • 若用户没有点赞过，则记录此次点赞行为。
  • 若用户曾经点赞过，则删除用户点赞记录。
  • @param username 用户名 */ void like(String username);

  /**

  • 返回所有点赞的用户名
  • @return 用户名数组 */ String[] getLikeUsers();

}

class LikeRecorderImpl implements LikeRecorder {

private HashSet<String> set = new HashSet<>();
// write your code here......
@Override
public void like(String username){
    if(set.contains(username)){
        set.remove(username);
    }else{
        set.add(username);
    }
}

@Override
public String[] getLikeUsers(){
    return set.toArray(new String[0]);
}

}